A protective effect of milk fat globule EGF factor VIII (MFG-E8) on the spontaneous fusion of milk fat globules in breast milk

We report here that the MFGs in the milk of MFG-E8-deficient mice fused each other and turned into abnormally large size of lipid droplets within ~48 h after being secreted into mammary alveolar lumen in situ or being incubated at 37°C in vitro. This biophysical degeneration of MFGs in the MFG-E8-deficient milk was efficiently rescued in vitro by adding the milk serum of wild-type mice, isolated MFG-E8 or annexin V. Moreover, addition of ethylenediaminetetraacetic acid (30 mM) also protected the MFG fusion remarkably in vitro. In addition, bovine MFGs also fused each other when isolated from milk serum, and the fusion was inhibited by adding isolated MFG-E8 or mouse milk serum, but not the milk serum of MFG-E8-deficient mice. MFG-E8 in breast milk may mask the phosphatidylserine exposed on the surface of MFGs with time after secretion and thereby suppress the membrane fusion among MFGs resulting in the enlargement of MFGs in the breast milk.

Source: Journal of Biochemistry - June 30, 2015 Category: Biochemistry Authors: Yasueda, T., Oshima, K., Nakatani, H., Tabuchi, K., Nadano, D., Matsuda, T. Tags: Regular Papers Source Type: research